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United States Patent |
5,269,829
|
Meyer
|
December 14, 1993
|
Method for accelerated aerobic decomposition of vegetative organic waste
material
Abstract
A method for aerobic decomposition of vegetative organic waste material
including high flow-rate aeration, compaction of the organic material, and
continual percolation of moisture released therefrom in a collapsible,
portable, bag container to provide beneficial soil amendments,
fertilizers, and supplemental heat sources.
Inventors:
|
Meyer; Donald W. (Ixonia, WI)
|
Assignee:
|
Compost Technologies, Inc. (Watertown, WI)
|
Appl. No.:
|
969509 |
Filed:
|
October 30, 1992 |
Current U.S. Class: |
71/9; 53/111R; 53/428; 53/434; 71/23 |
Intern'l Class: |
C05F 017/00; C05F 005/00; C05F 009/00; C05F 009/04 |
Field of Search: |
71/23
|
References Cited
U.S. Patent Documents
2867521 | Jan., 1959 | Jeffreys | 71/9.
|
2969279 | Jan., 1961 | Pierson | 71/9.
|
3138447 | Jun., 1964 | Eweson | 71/9.
|
3276845 | Oct., 1966 | Redman | 23/259.
|
3756784 | Sep., 1973 | Pittwood | 23/259.
|
3930799 | Jan., 1976 | Eweson | 23/259.
|
3934999 | Jan., 1976 | Meier | 71/9.
|
4100023 | Jul., 1978 | McDonald | 71/9.
|
4230676 | Oct., 1980 | Tayler et al. | 422/62.
|
4255389 | Mar., 1981 | Jung et al. | 422/209.
|
4302546 | Nov., 1981 | Schlichting, Jr. | 435/315.
|
4326874 | Mar., 1982 | Burklin | 71/9.
|
4436817 | Mar., 1984 | Nemetz | 435/313.
|
4666854 | May., 1987 | Sugiura | 435/313.
|
4687645 | Aug., 1987 | Harvey | 422/184.
|
Other References
"Solar Forced-Air Compressor" by Prof. John J. Poluhowich, A. Scott Whyte &
Norman Adelkopt; Tropical Research--Mar., 1986.
|
Primary Examiner: Lander; Ferris
Attorney, Agent or Firm: Reinhart, Boerner, Van Deuren, Norris & Rieselbach
Parent Case Text
RELATED APPLICATION
This application is a continuation of copending U.S. patent application
Ser. No. 07/738,958, filed on Aug. 1, 1991 and now abandoned.
Claims
I claim:
1. A method for aerobically decomposing large volumes of vegetative organic
material, comprising:
providing a substantially collapsible, moisture-retentive, and portable
container having at least one open end and an upper portion with a
plurality of openings, said container connected at said openings to means
for variable high-rate air intake and vent means comprising a plurality of
aperatures sufficient in number and dimension to maintain homeostatic
airflow and aerobic decomposition temperatures;
packing the container with vegetative organic material having a releasible
moisture content at pressure of about 0.1-10.0 pounds per square inch,
whereby the organic material has a density of about 10-75 pounds per cubic
foot such that said material is substantially heat retentive, permits
movement of moisture therethrough, and maintains homeostatic airflow and
aerobic decomposition temperatures;
closing the open end of the container such that said container is
substantially moisture-retentive;
aerating the container substantially continuously through said openings at
a rate of about 200-1500 cubic feet per minute to control and maintain
sufficient aerobic decomposition temperatures; and
precolating releasible moisture throughout the organic material.
2. The method of claim 1 wherein the container is a substantially
moisture-retentive bag.
3. The method of claim 1 wherein the air-intake means comprises a discharge
blower and a series of conduits extending therefrom, said conduits
inserted through said container openings and extending substantially to
the bottom portion of the container.
4. The method of claim 3 wherein the portions of said conduits inserted
into the container are perforated.
5. The method of claim 1 wherein the organic material is aerated at a rate
of about 400-1100 cubic feet per minute and a static pressure of at least
0.5 inches of water.
6. The method of claim 5 wherein the organic material is aerated at a rate
of about 600 cubic feet per minute and a static pressure of about 0.5-1.5
inches of water.
7. The method of claim 1 wherein the organic material includes a bulking
agent.
8. The method of claim 7 wherein the bulking agent is about 10-70 percent
by weight of the organic material.
9. The method of claim 8 wherein the bulking agent is about 25-50 percent
by weight of the organic material.
10. The method of claim 1 wherein the organic material is packed with a
pressure of about 0.5-5.0 pounds per square inch.
11. The method of claim 10 wherein the packed organic material has a
density of about 25-35 pounds per cubic foot.
12. The method of claim 1 wherein percolation involves release of said
moisture content from the organic material during decomposition,
vaporization of the same by heat generated thereby, and condensation on
the container.
13. The method of claim 1 further comprising monitoring the internal
temperature of said organic material to determine the aeration rate
required for optimal decomposition.
14. The method of claim 1 further comprising injecting water into said
organic material to achieve optimal decomposition.
Description
FIELD OF THE INVENTION
This invention is related generally to the aerobic decomposition of
vegetative organic waste material and, more particularly, to a method and
apparatus used therewith to greatly accelerate such decomposition.
BACKGROUND OF THE INVENTION
The past several years have been witness to a renewed interest in the
environment. The special attention afforded so-called "green" products and
methods of production attest to the fact that commercial viability is not
always contrary to resource conservation. Often, environmental regulations
and/or restrictions provide the impetus for innovative methods and
apparatus.
A case in point is the recent legislative trend toward banning landfill
disposal of various waste materials. Of course, many hazardous chemical
and biological wastes have long been restricted, but with available
landfill space becoming increasingly scarce, common yard and various
related forms of vegetative organic wastes will soon require alternate
means of disposal. Municipalities and other levels of government are faced
with an urgent and growing problem.
The advantages of composting or decomposing organic material to provide
various fertilizers and/or soil amendments are well-known. The challenge
has always been one of adapting backyard garden techniques to processes
capable of handling large volumes, such as those typically generated by
municipalities, in a safe, environmentally-conscious manner. The problem
has been compounded in recent years by the budgetary constraints under
which most governmental units operate. Economy and fiscal responsibility
are, thus, additional on-going concerns in the art.
The prior art includes a variety of attempts to produce an apparatus or
derive a method to decompose or compost waste organic material through the
metabolic activity of aerobic bacteria. Most provide only limited success.
U.S. Pat. No. 3,934,999 describes use of an aqueous bacterial inoculant
and depends on absorption of solar heat to decompose a small amount of dry
organic material placed in a common home garbage bag. A number of evenly
spaced apertures in the bag allow passive movement of air and facilitate
composting. Periodic, manual agitation of material is required and
possible only because the method is restricted to exceedingly small
volumes.
U.S. Pat. No. 3,756,784 is directed to a complex apparatus for the
sequential composting of domestic refuse and includes a plurality of
essentially immovable vertically-disposed chambers, each with its own
agitator, water supply, and air supply. The rates of addition of air and
water are a function of temperature and carbon dioxide levels in each
chamber. A varying combination of air, water, and agitation must be
accurately administered to maintain aerobic conditions in each chamber.
U.S. Pat. No. 4,302,546 discloses a constantly rotating tank-like apparatus
to recycle animal wastes. Carbonaceous filler materials must be added to
control moisture content. Continual, low flow-rate aeration facilitates
decomposition. Exhaust air is past through a scrubber to eliminate
foul-smelling components which would otherwise pollute the surrounding
atmosphere.
U.S. Pat. Nos. 3,138,447 and 3,930,799 are directed to a process and
apparatus, respectively, for producing fertilizer from organic and
inorganic municipal garbage. Low flow-rate aeration is aided by constant
"tumbling" to prevent air channel formation. Moisture is first introduced
to enhance decomposition via the addition of sewerage sludge then removed
during a later drying phase. Temperature and carbon dioxide levels are
monitored throughout decomposition.
U.S. Pat. No. 4,230,676 describes an apparatus and method for decomposition
using exposed windrows of organic material. Integral to both the apparatus
and method is a microprocessor which monitors temperature, air/moisture
content, and pH of the windrowed material. A complex, adjustable injector
configuration makes any additions/corrections necessary in response
thereto.
Various prior art sources teach the use of a Beltsville or modified
Beltsville system, which is necessarily limited to composting small
volumes of material under tropic or warm weather conditions through use of
a solar forced-air collector. Low-rate aeration and initial addition of
water to loosely-arranged material characterize methods of this type. The
apparatus used therewith typically includes overlapping sheets of plastic
to catch rain water.
These are but a few examples of the prior art. Other methods and/or
apparatus may be characterized as involving extensive waste analysis and
monitoring, supplemental heat supplies, and agitation, among other steps
or components. As is evident, a considerable number of drawbacks and
problems exist in the prior art relating to the beneficial decomposition
of organic waste materials.
There is a need for an improved aerobic decomposition method to more fully
utilize the advantages associated with re-using waste materials of the
sort and, at the same time, provide for a feasible, environmentally-safe
alternative to landfill disposal.
OBJECTS OF THE INVENTION
It is an object of this invention to provide a method of accelerated
decomposition of vegetative organic waste material, overcoming some of the
problems and shortcomings of the prior art, including those mentioned
above.
Another object of this invention is to provide a method for quick,
efficient decomposition of large volumes of vegetative organic material as
a useful alternative for landfill disposal.
Another object of this invention is to provide a method of decomposition
which may be used with large volumes of organic material in conjunction
with a light-weight, portable apparatus.
Another object of this invention is to provide a method of decomposition
which does not require the use of a complex, expensive apparatus
comprising numerous constantly-moving components prone to costly repair
and maintenance.
Another object of this invention is to provide a method of decomposition
such that the desired degree of bacterial degradation may be achieved
without resort to complex and/or computerized analytic techniques.
Another object of this invention is to provide an odor-free method of
decomposition without use of pollution-control or abatement devices.
Another object of this invention is to provide a method of decomposition
which does not necessitate either a chemical or bacterial inoculant or an
extraneous heat source such as solar radiation.
Another object of this invention is to provide a method of decomposition
which does require the use of either dry, absorptive filler materials or
sewage sludge to obtain suitable moisture levels.
These and other important objects will be apparent from the descriptions of
this invention which follow.
SUMMARY OF THE INVENTION
This invention is a method for accelerated decomposition of large volumes
of vegetative organic waste material. It overcomes certain well-known
problems and deficiencies, including those outlined above. An important
aspect of this invention is a novel combination of constant high-flow rate
aeration, material compaction, and continual moisture percolation, all of
which are used in conjunction with a unique container apparatus to provide
not only a viable alternative to landfill disposal, but means to produce
useful soil amendments, fertilizers, and a source of supplemental heat.
The inventive method allows for quick, cost-effective aerobic
decomposition, such that the advantages associated with recycling
materials of this sort may be more fully realized.
This invention is a method of aerobically decomposing large volumes of
vegetative organic material including (1) providing a substantially
collapsible or portable container having at least one open end, vent
means, and an upper portion with a plurality of openings, said container
connected at said openings to means for variable high-rate air intake; (2)
packing the container with vegetative organic material having a moisture
content; (3) closing the open end of the container such that it is
substantially moisture-retentive; (4) aerating the container continuously
through the openings at a rate of about 200-1500 cubic feet per minute;
and (5) percolating moisture throughout the organic material.
In preferred embodiments of this invention, the container is a flexible,
substantially moisture-impermeable bag; and the air-intake means is a
discharge blower connected to a series of conduits such that the conduits
are inserted through the container openings and extend substantially to
the bottom of the bag. In highly preferred embodiments, the conduits are
perforated in those portions extending into the bag.
In preferred embodiments of this invention, the organic material is aerated
at a rate of about 400-1100 cubic feet per minute and a static pressure of
at least 0.5 inches of water. In highly preferred embodiments, the organic
material is aerated at a rate of about 600 cubic feet per minute and a
static pressure of about 0.5-1.5 inches of water.
The organic material decomposed through the method of this invention
preferably includes a bulking agent in about 10-75% by weight of the
organic material. In highly preferred embodiments, the weight of the
bulking agent is about 25-50% of the total weight of the organic material.
In preferred embodiments of this invention, the organic material is packed
into the bag with a pressure of about 0.1-10.0 pounds per square inch. In
preferred embodiments, the packing pressure is about 0.5-5.0 pounds per
square inch, such that the packed material has a density of about 10-75
pounds per cubic foot. In highly preferred embodiments, the packed
material has a density of about 25-35 pounds per cubic foot such that it
retains heat generated during composition yet allows movement of moisture
of air therethrough.
As a final step, this method includes percolation whereby moisture content
is released from the organic material during composition, then vaporized
by heat generated and condensed on the container.
The method of this invention also contemplates monitoring the internal
temperature of the organic material to determine the aeration rate
required for optimal decomposition. Likewise, the method may also include
injecting water into the organic material to achieve optimal
decomposition.
As previously noted, the method of decomposition as revealed through this
invention, has certain advantages, most of which relate directly to the
ease and rate at which a useful degree of decomposition may be achieved.
Natural composting requires up to two years under typical conditions. This
inventive method permits large-scale decomposition in a fraction of that
time, such that volumes approximating 1,000 cubic yards of waste may be
sufficiently decomposed within four months or less with a concomitant
volume reduction of nearly 80%.
Conservative estimates indicate a typical city of 750,000 may produce, won
an average annual basis, 45,000 tons of yard and related waste--waste
which would otherwise be landfilled. When considered with the fact useful
by-products and a supplemental heat source may be derived from what would
otherwise be a costly refuse problem, the benefits available through use
of this method to municipal governments, as well as others
similarily-situated, are immediately evident.
As detailed more fully below, aerobic bacterial decomposition is a very
exothermic process. Temperatures exceeding 130.degree. F. are typically
generated. As such, the high flow-rate aeration component of this
inventive method may be used to provide a supplemental heat source for a
variety of functions, including the winter-heating of a greenhouse or
similar such structure in which case the organic material decomposed is
that produced during the growing season.
Regardless, the material remaining upon completion of decomposition is a
useful soil amendment and fertilizer for residential or agricultural use
in that it provides excellent aeration and water-retention qualities and
nutrients to any soil to which it is introduced. It may also be used in
conjunction with various road and highway projects to prevent surface
erosion.
Unlike methods of the prior art, that revealed herein may be employed
without an expensive and complex apparatus. The preferred bag container
used in conjunction with this method is relatively inexpensive. It may be
used to decompose large volumes of organic waste material, yet may be
purchased at a fraction of the cost of conventional equipment. Costly
repair and down-time associated with apparatus of the prior art are
avoided by an absence of components moving against the weight of a large
volume of waste material. Furthermore, it is light-weight and portable
such that it may be relocated once decomposition is complete.
As significant as these attributes are, perhaps the most important benefits
derived from use of the bag apparatus of this invention are those more
directly related to the environment. The preferred bag container
eliminates wind-borne debris and prevents potentially-hazardous
decomposition leachates from running into and contaminating surface water.
Together with odorless decomposition, these advantages make use of this
method ideal for municipalities composting near residential areas.
The preferred discharge blower component effects high flow-rate aeration
and is a useful compliment to the preferred bag container. Light weight
and simplicity of design promote easy assembly and allow both the blower
and conduits to be moved with the preferred bag when or as needed.
Low cost and maintenance are important advantages associated with use of
the preferred apparatus of this invention. Likewise, the water injector
and temperature monitoring means which may be used with the method of this
invention are also effective without significantly increasing the cost of
decomposition, an important consideration to municipalities and others
restrained by budget limitations.
Aerobic decomposition is predominantly a function of the internal
temperature of the waste material and aerobic bacteria indigenous to it,
and proceeds effectively at a temperature of about 130.degree.-160.degree.
F. As a rule, when the temperature drops below this range bacterial
activity declines; excessive heat promotes anaerobic decomposition. An
inventive aspect of this method includes control of decomposition through
rate of aeration. It has been established that changes in aeration rates
may be used to effect almost-immediate response in mass temperature. As a
result, the internal temperature of the decomposing material be adjusted
to within 5.degree. F. of the desired temperature condition without
resorting to expensive, complex microprocessors or other analytic methods
of the prior art.
The need for complete aerobic decomposition is immediately obvious once the
internal temperature of the organic mass exceeds the desired range for any
length of time. The gaseous by-products of anaerobic decomposition tend to
be foul-smelling and are widely-considered a form of pollution completely
unacceptable to those unfortunate to reside in close proximity. The method
of this invention prevents anaerobic bacterial activity such that
decomposition proceeds effectively without offensive odors or the need for
auxiliary scrubbing or control devices.
As inferred above, bacteria indigenous to the waste material may be
utilized without adding extraneous decomposition-enhancing chemicals or
bacterial cultures. Inasmuch as inoculants of this sort are relatively
expensive and require additional monitoring, a considerable cost-savings
compared to methods of the prior art may be realized.
This inventive method anticipates the possibility that the addition of
moisture may be required to enhance the rate of decomposition with certain
extremely dry waste materials. However, with most organic wastes, the
natural moisture content has been found sufficient, foregoing the need to
add sewerage sludges or other high-water-content materials which may have
a corrosive, deleterious effect on any apparatus used. Conversely, too
much water does not impede this method. Because excessive moisture only
enhances percolation and decomposition, filler materials of the prior art
are not needed to absorb water.
The method of this invention would not seem appropriate for the aerobic
decomposition of organic material. Aeration systems of the prior art
stress the use of low flow-rates in combination with loosely-arranged
waste material either constantly or periodically agitated to encourage
aerobic conditions. The use of high flow-rate aeration with compacted
material and continual percolation of moisture is contrary to the art, and
the excellent results obtained were quite unexpected.
BRIEF DESCRIPTION OF THE DRAWINGS
A preferred embodiment of an apparatus suitable for employing the method of
this invention is shown in the accompanying drawings, of which:
FIG. 1 is a sectional view of the apparatus;
FIG. 2 is a top view of the apparatus; and
FIG. 3 is a side view of the apparatus.
DETAILED DESCRIPTIONS OF THE PREFERRED EMBODIMENTS
The drawings illustrate the preferred embodiment of an apparatus which may
be used to employ the method of this invention. The apparatus includes bag
10 and air conduit 16 attached to blower 20.
As best shown in FIG. 1, bag 10 is provided with a plurality of
substantially evenly-spaced openings 14 through which air conduits 16 are
inserted. Joints 18 allow conduits 16 to be used in a series
configuration. Once bag 10 is sufficiently packed with organic waste
material, fastener means 12 secures the open end, creating a substantially
moisture-retentive container.
Air conduits 16 are connected to discharge blower 20 which, when in
operation, provides high flow-rate aeration throughout bag 10. Conduits 16
extend substantially the depth of bag 10. Perforations 22 spaced along
conduits 16 allow air forced therethrough to permeate the vegetative
matter. Homeostatic air flow is achieved through incorporation of exhaust
vents 24, preferably located in the upper portion of bag 10 between
conduits 16. Temperature monitoring means may also be used in conjunction
with the method of this invention. In such case, apertures 26, as shown in
FIG. 1, are made through bag 10 for insertion of such means into the
material mass.
As best shown in FIGS. 2 and 3, water injection means 28 may be employed
with the method of this invention. If so, such means may be inserted
through holes 30 into an upper portion of bag 10 and the vegetative matter
contained therein. Preferably, injection means 28 is in a series
configuration such that it is aligned between and at right angles to
conduits 16.
High flow-rate aeration and an apparatus to provide the same are essential
to the aerobic decomposition described herein. In accordance with this
invention, a container packed with vegetative organic material is aerated
continuously at a rate of about 200-1500 cubic feet per minute to obtain
optimal aerobic decomposition conditions. At aeration rates below this
range, anaerobic bacteria and odiferous metabolic by-products predominate;
aeration in excess of this rate appears to create conditions disruptive to
aerobic bacterial activity.
In preferred embodiments of this invention, air is forced through a
container apparatus at a rate of about 400-1100 cubic feet per minute. In
highly preferred embodiments, accelerated decomposition may be achieved
with a flow rate of about 600 cubic feet per minute. Air flow must be
conducted at a sufficient static pressure to achieve the desired aerobic
decomposition. Pressures of at least 0.5 inches of water are needed to
force the preferred volumes of air through the air conduits. Studies show
that pressures of 0.5-1.5 inches of water provide excellent results.
Bulking agents such as straw, wood chips, and the like may be used with the
method of this invention. Inclusion of these materials promote aeration
and enhance aerobic decomposition by creating air spaces and passages
within the vegetative mass. As a result, optimal aerobic temperatures may
be obtained more readily and adjusted by air-flow rates more efficiently.
As stated above, a bulking agent may comprise about 10-70 percent by weight
of the vegetative organic material to be decomposed. The exact amount
utilized depends, in large part, on the compaction susceptibility of the
vegetative material which, in turn, depends upon its moisture content. It
has been found with most waste materials the bulking agent should be about
25-50 percent of the total weight of the organic material. The exact
amount used may vary with the air flow-rate utilized.
It is essential that the organic material be compacted into the container
apparatus to retain heat generated during decomposition and further
enhance aerobic bacterial activity. Unlike methods of the prior art, most
of which include means to prevent compaction, a preferred method of this
invention entails filling a container with moderate pressure. The pressure
utilized varies and depends, in part, on the moisture content of the
material to be decomposed.
Typically, pressures of about 0.5-5.0 pounds per square inch are employed
during packing process. With materials such as grasses which have a
relatively high moisture content, the pressure used will tend toward the
lower end of this range; higher pressures will result in a mass density
which may preclude sufficient aeration and lead to unwanted anaerobic
decomposition. Conversely, materials such as dry leaves are packed with
pressures near the upper end of the aforementioned range. In these
situations, too little pressure results in a material mass with
insufficient heat retention qualities. To some degree, packing pressures
may be modified for a given material and moisture content through
adjustment of the amount of bulking agent used. Packing may be
accomplished through use of apparatus well-known to those made familiar
with this invention. Blowers and auger-type devices which supply
sufficient, constant pressures of the sort described herein may be
successfully.
Constant high flow-rate aeration is accompanied by continual percolation of
moisture throughout the material mass. The preferred bag container used in
conjunction with this inventive method permits accumulation of moisture as
it is released from the decomposing material. As decomposition proceeds,
the internal temperature rises and the released moisture vaporizes,
passing through the material and condensing on the surface of the bag
container. The combination of repeated percolation of moisture and high
flow-rate aeration enhances aerobic bacterial activity and accelerates
decomposition.
To decompose of especially dry vegetative material, the method of this
invention contemplates initial injection of water to approximate a
suitable moisture content equivalent to about 20-65% of the weight of the
material. Typically, only one such injection is required as the moisture
is thereafter continually recycled through the percolation step described
above.
Preferred bag 10 may be made using a variety of materials, including
polyethylene and other similar durable, flexible plastics. Any material
utilized must resist tears when openings are introduced as exhaust vents
or for the insertion of aeration conduits, yet must be flexible and
extendable enough to accommodate the collection of a significant amount of
moisture once decomposition begins. It has been found that a polyethylene
bag with a thickness in excess of 6 mil provides excellent results under
the decomposition conditions employed with this method. Thinner materials
do not provide the strength and flexibility needed to process large
volumes of waste material.
Preferred polyethylene bags may range from 10-250 feet in length. For
volumes effectively decomposed through use of this method, a 100-foot bag
provides excellent results. Such containers are available from sources
well known to those skilled in the art and include AG-BAG Corporation of
Warrenton, Oreg., among others.
Blower 20 and conduits 16 may also be obtained from a variety of sources
well-known to those made aware of this invention. In particular, excellent
results will be obtained through use of a blower with means to vary
flow-rates such that internal mass temperatures may be adjusted as needed
to provide optimal decomposition conditions. One such blower, suitable for
employing the method of this invention, is available from Dayton Electric
Manufacturing Company of Chicago, Ill.
While the principles of this invention have been described in connection
with specific embodiments, it should be understood clearly that these
descriptions are made only by way of example and are not intended to limit
the scope of the invention. For example, the container apparatus used in
conjunction with this method may include various mesh-type materials which
permit retention of heat and allow condensation of internal moisture.
Likewise, vegetative materials are not necessarily limited to the yard and
related waste described. Waste paper, lake algae, and a variety of other
vegetative organic materials are suitable for decomposition through the
method of this invention.
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